On Sat, Oct 15, 2011 at 07:21:34PM -0700, Lochadio Who wrote:
>
> You could easily run four 100 amp automobile alternators off a 4 horse lawn
> mower engine.
That's a little optimistic. :) Since 100A * 15V = 1500W, (a.k.a. 2HP),
two of these at full load would max out a 4HP engine, which would have
to be carefully tuned and run at a fixed speed to put out that full 4HP
(and it would have a rather short life, running at that max output all
the time; gas engines aren't very good at that kind of thing.) Add in
the friction losses, and even two 100A alternators is a bit much.
As I recall, Nigel Calder estimates that a 150A alternator at a 5HP load
on the engine. That may be a bit too generous, but it's in the general
area. On the other hand, a civil engineer friend of mine designed a
block of apartment houses for a Third World country which provided all
the needed electricity, heat, and hot water they needed off a single VW
car engine (30HP or so.) Obviously, they have to be rather conservative
in how they use and allocate the output, but I found that pretty
impressive.
--
Ben Okopnik
-=-=-=-=-=-
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